3x(x-12)=21

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Solution for 3x(x-12)=21 equation:


Simplifying
3x(x + -12) = 21

Reorder the terms:
3x(-12 + x) = 21
(-12 * 3x + x * 3x) = 21
(-36x + 3x2) = 21

Solving
-36x + 3x2 = 21

Solving for variable 'x'.

Reorder the terms:
-21 + -36x + 3x2 = 21 + -21

Combine like terms: 21 + -21 = 0
-21 + -36x + 3x2 = 0

Factor out the Greatest Common Factor (GCF), '3'.
3(-7 + -12x + x2) = 0

Ignore the factor 3.

Subproblem 1

Set the factor '(-7 + -12x + x2)' equal to zero and attempt to solve: Simplifying -7 + -12x + x2 = 0 Solving -7 + -12x + x2 = 0 Begin completing the square. Move the constant term to the right: Add '7' to each side of the equation. -7 + -12x + 7 + x2 = 0 + 7 Reorder the terms: -7 + 7 + -12x + x2 = 0 + 7 Combine like terms: -7 + 7 = 0 0 + -12x + x2 = 0 + 7 -12x + x2 = 0 + 7 Combine like terms: 0 + 7 = 7 -12x + x2 = 7 The x term is -12x. Take half its coefficient (-6). Square it (36) and add it to both sides. Add '36' to each side of the equation. -12x + 36 + x2 = 7 + 36 Reorder the terms: 36 + -12x + x2 = 7 + 36 Combine like terms: 7 + 36 = 43 36 + -12x + x2 = 43 Factor a perfect square on the left side: (x + -6)(x + -6) = 43 Calculate the square root of the right side: 6.557438524 Break this problem into two subproblems by setting (x + -6) equal to 6.557438524 and -6.557438524.

Subproblem 1

x + -6 = 6.557438524 Simplifying x + -6 = 6.557438524 Reorder the terms: -6 + x = 6.557438524 Solving -6 + x = 6.557438524 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '6' to each side of the equation. -6 + 6 + x = 6.557438524 + 6 Combine like terms: -6 + 6 = 0 0 + x = 6.557438524 + 6 x = 6.557438524 + 6 Combine like terms: 6.557438524 + 6 = 12.557438524 x = 12.557438524 Simplifying x = 12.557438524

Subproblem 2

x + -6 = -6.557438524 Simplifying x + -6 = -6.557438524 Reorder the terms: -6 + x = -6.557438524 Solving -6 + x = -6.557438524 Solving for variable 'x'. Move all terms containing x to the left, all other terms to the right. Add '6' to each side of the equation. -6 + 6 + x = -6.557438524 + 6 Combine like terms: -6 + 6 = 0 0 + x = -6.557438524 + 6 x = -6.557438524 + 6 Combine like terms: -6.557438524 + 6 = -0.557438524 x = -0.557438524 Simplifying x = -0.557438524

Solution

The solution to the problem is based on the solutions from the subproblems. x = {12.557438524, -0.557438524}

Solution

x = {12.557438524, -0.557438524}

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